Error when running SuperDuper via shell script

[dnanian]

You're right -- the line does have to be "unmount force", but when I tried it on the command line it worked:

[g5:~] dnanian% diskutil unmount force /dev/disk2s2
Volume /dev/disk2s2 force unmounted
[g5:~] dnanian%

(where /dev/disk2s2 was a mounted image -- worked fine)

I then took the line, with the swap of force and unmount, and did the part up to the erase, manually substituting:

sh-2.05b$ JNLD=$(diskutil info "/Volumes/Macintosh HD 1" | grep -q -F Journaled; echo $?);diskutil unmount force "/dev/disk2s2";diskutil mount "/dev/disk2s2";
Volume /dev/disk2s2 force unmounted
Volume /dev/disk2s2 mounted

So, it looks like it works... maybe your edit changed the syntax a bit?